Method of sequentially separating a medium into different components

ABSTRACT

A method and vortex separator for sequential separation of a medium into different components by means of centrifugal force in a vortex array (2, 2) in a manner that part of the vortex flow (71) proceeds from the outer portions of a vortex (2) into the outer portions of a following vortex (2) and in individual vortexes (2) particles having a major mass concentrate in the outer portions of a vortex and those having a minor mass concentrate in the central portions of a vortex. For increased separation capacity the successive vortexes (2) of a vortex array (2, 2) are backed up substantially on each other while rotating in opposite directions and the flow (71) between individual vortexes is allowed to pass without any substantial movements in the direction of a vortex axis (49).

This is a continuation of application Ser. No. 883,042, filed on July11, 1986, now U.S. Pat. No. 4,702,846, which is a continuation ofapplication Ser. No. 689,037, filed on Jan. 8, 1985, now abandoned,which is a continuation of application Ser. No. 469,518, filed on Feb.24, 1983, now abandoned.

A method of and apparatus for sequentially separating a medium intodifferent components.

The present invention relates to a method of and apparatus forseparating a medium into different components by means of centrifugalforce in a vortex array, so that part of the vortex flow proceeds fromthe outer portions of a vortex into the outer portions of a followingvortex, and in individual vortexes particles of major mass concentratein the outer portions of a vortex and those of minor mass concentrate inthe inner portions of a vortex.

The term "medium", as used in this specification, is meant to coverpowdered and fibrous solid subtances, flowing liquids, liquid drops andgases as well as various mixtures thereof. Similarly, the term"particle" is meant to cover solid particles, liquid drops, liquidmolecules, gas molecules and gas atoms. The term "a particle of majormass" is intended to also cover all those particles, which behave in avortex the same way as a particle of major mass, e.g. as a result ofshape, even though in reality there would be no difference in mass orthat difference would be opposite.

Prior known are vortex separators of various designs, wherein thevortexes are usually confined by cylindrical or conical surfaces. Thewall of a vortex chamber is generally flat and continuous in thetravelling direction of a vortex. Most of the prior art vortexseparators employ a screw-shaped helical travelling path, often also twoconcentric screw threads if the question is about a cone. Examples of asequential vortex array separator are disclosed in U.S. Pat. Nos.1,660,687, 1,660,685, 3,948,771, 535,099 and 2,701,056. The separatingvortexes, which collide with each other, have been disclosed in theFinnish Patent application No. 81337.

A drawback in the prior art vortex separators is a strong frictionalresistance, generated between a stationary wall and a fast movingvortex. Such friction creates considerable energy losses and leads todisturbing turbulence near the wall which messes up the separationresult already achieved. The frictional resistance is vigorouslyincreased by the helicity of turbulent motion, the particles beingforced to circulate a plurality of cycles, the frictional distanceadjacent to the wall becoming long. Frictional resistance has beensubstantially reduced by the solutions set out in the Finnish Patentapplication No 813387. However, the use of a helix, as shown e.g. inFIG. 16, will only result in a halfway solution with plenty offrictional distance of the wall remaining because of a plurality ofcycles.

Due to the strong wall friction, the turbulent motion graduallydecelerates and the centrifugal force decreases, leading to the fall ofseparating power. Therefore, long separator arrays cannot be madesuccessful with prior art technology, when turbulent motion graduallydies away. The most difficult separating tasks would require quite longarrays of vortexes, wherein concentration into different components iseffected gradually.

In the prior art vortex arrays the vortexes are not substantially backedup on each other for the reduction of friction. The small slits that arebeing used are just passages for particles from one vortex to another.

The prior art vortex separator systems are structurally complicated,require a lot of structural material and are inconvenient tomanufacture. This is particularly true with conical equipment whoseprice excessively high considering how simple the apparatus in principleis. The configuration of a system comprising a plurality of apparatusunits is generally irregular with a lot of waste space remaining betweensaid units. The equipment cannot always be installed in optimumlocations because of the great demand of space.

In conical vortex separators, heavy particles are sought to be separatedinto the outer portions of a vortex but, due to concentric helixes, theheavy and light components are brought very close to each other sincethe inner vortex, which contains the light component, makes its turnnear the top of a cone. This creates a paradoxical situation, in whichthe components that are already separated far from each other are nearlycombined anew. A result of this is naturally mixing of variouscomponents and a poorer final separation.

Most of the prior art vortex separators are provided with a tangentialsupply duct that is relatively flat with respect to the overall heightof the apparatus. Due to the small supply port, the capacity remainssmall and the apparatus takes a lot of space. The height of a supplyport in the prior art equipment is generally about one tenth of theheight of an entire apparatus or even a lot smaller than that.

An object of this invention is to alleviate the above drawbacks and thatis achieved by applying the method of the invention in a manner that thesuccessive vortexes of an array of vortexes are substantially supportedor backed up on each other while rotating in opposite directions and theflow between individual vortexes is allowed to pass without substantialaxial movements.

The equipment for carrying out the method of the invention will bedescribed hereinbelow in the appended claims.

The invention can be applied to virtually all separating tasks. Examplesinclude separation of solids from gases, separation of solids from aliquid, assortment and grading of solids particles, thickening andconcentrating in general, fractionating of gas mixtures, separation ofemulsions etc.

The invention is illustrated by the accompanying figures.

FIG. 1 shows an array of vortexes according to the invention, in whichsuccessive vortexes back up on each other and rotate in oppositedirections.

FIG. 2 is a section along line II--II in FIG. 1.

FIG. 3 is an alternative section along line II--II in FIG. 1.

FIG. 4 shows a vortex system, in which four arrays of vortexes of theinvention are positioned parallel to and backed up on each other.

FIG. 5 shows a system consisting of two arrays of vortexes of theinvention, with the vortexes going smaller in diameter.

FIG. 6 shows a system consisting of two arrays of vortexes of theinvention, in which the impact edges against the flow are rounded.

FIG. 7 shows arrays of vortexes of the invention which branch in threedirections from a single supply vortex.

FIG. 8 shows arrays of vortexes of the invention, comprising severalbranchings and conjunctions.

FIG. 9 shows two arrays of vortexes of the invention which branch andre-unite.

FIG. 10 shows an array of vortexes of the invention with the vortexesalternately disposed on either side of the average longitudial axis ofan array.

FIG. 11 shows a vortex system with two vortex arrays of FIG. 10 combinedin parallel relationship.

FIG. 12 shows an array of vortexes of the invention, in which the lastvortex is not fitted with outlet for a light component.

FIG. 13 shows an array of vortexes of the invention, in which the lastvortex is fed with a scavenging medium.

FIG. 14 shows in principle the deviation of a vortex center from thegeometric center of a vortex chamber.

The essential substance of this invention is to simplify and boost theactual separation compared to the prior art centrifugal methods, e.g.cyclones. The primary objective is to reduce friction between vortexesand a wall to eliminate the drawbacks resulting therefrom. In addition,the outer vortex with its heavy components is to be kept as far away aspossible from the vortexes' central portions and the light componentstherein, whereby said components cannot mix with each other. To thisend, some of the walls confining the vortexes on their outer peripheryare removed. The support action, which urges the vortexes invards and isexerted by the walls, is compensated for by bringing two successivevortexes of an array to back up on each other, the centrifugal forces ofsaid vortexes holding them together. A result of the opposite rotatingdirections of successive vortexes is that the travelling direction ofmedium particles is the same where the wall has been removed, thuseliminating the generation of noticeable turbulence. The running speedsof individual vortexes tend to equalize themselves automatically.

A further object of the invention is to reduce the number of requiredrotations in a vortex, particularly those of the heavy componentadjacent to the wall. By providing as simple and quick an exit aspossible for the heavy component through the ports between vortexes, itis possible to alleviate abrasion drawbacks and also to reduce frictionthereby. By passing a tangential supply or feed into a vortex array overthe entire height or almost the entire height of vortexes, it ispossible to substantially eliminate the need of axial movements, e.g.the helical paths can be eliminated from the outer portions of vortexes.This is also facilitated by making the heavy fraction discharge oroutlet tangential and as high as the vortexes.

Another object of the invention is to intensify centrifugal force in theouter portions of a vortex at the points of sudden reversal of a vortexcreated in the proximity of removed wall sections. The reason for suchreversal points is that the cammon section of successive vortexes tendsto build up a flat surface which is a chord for individual vortexes,whereby also the travelling paths become at this point linear, thuscreating in the travelling paths of the outer portions of a vortex ashorter than normal radius of rotation prior to and after such point.

The accompanying figures show examples of a few embodiments of theinvention and illustrate the way the invention is practiced. In reality,the invention can be practiced by applying a great number of variousembodiments. The designs and dimensions of the equipment set out in theinvention are chosen according to a given application. The choice can bebased on experimental studies and theoretical approach.

The following terms are used for the components illustrated in thefigures

1. wall of a vortex chamber

2. general running direction of a vortex

12. a tangential supply duct

13. outlet for a light component

39. a flow divider for separating individual vortexes from each other

40. an area where adjacent vortexes back up on each other

47. lid for a vortex chamber

49. central axis of a vortex

62. heavy component on the bottom of a chamber

63. a flow which by-passes a vortex as illustrated in principle

64. shut-off feeder

65. whirling motion of a scavenging medium in princple

66. supply pipe for a scavenging medium

67. geometric center of a vortex chamber

68. bottom of a vortex chamber

70. outlet for a hevy component

71. travelling path of a heavy component in principle

72. a rounded impact edge

73. average longitudinal axis for an array of vortexes

74. point of sudden change of flow direction.

FIG. 1 shows a vortex array separator, wherein successive vortexes 2 areessentially backed up by each other at points 40. Successive vortexflows 2 travel at such points 40 in a common direction, while therotating directions are opposite in axial view. A vortex array 2, 2, 2,2, 2 illustrated in the figure includes five successive vortexes. Thegeneral running direction of flow is in the figure from left to right.The supply is effected through a narrow supply duct 12, which covers theheight of an entire vortex, thus providing a high capacity. In the firstvortex, furthest left in array 2,2 ... , the heavy component tends towork its way to the outer periphery and on into the following vortex 2.The lightest fraction of a light component remains rotating in the firstvortex and gradually finds its way to central portions and into outlet13. In the second vortex 2 of array 2, 2 . . . , the heaviest componenttends to continue travelling still on the outer periphery but changing,however, the direction of curvature of motion 71 as compared to thefirst vortex 2. The heavy component tends to proceed from the secondvortex 2 to the right into the third vortex 2 of array 2, 2 . . . ,while part of the light component remains rotating in the second vortex2. The flow 2 rotating in the second vortex collides within a region 40with the outer portions of said first vortex 2 and by its centrifugalforce tends to urge particles of the first vortex towards the center ofsaid first vortex 2. The centrifugal forces of individual vortexes 2counter-act and vortexes 2 back up on each other within area 40 andretain the whirling motion without the support action of a wall 1.Similar phenomena take place between individual vortexes 2 of a vortexarray. If a particle of the heavy component and having a major massaccidentally remains rotating within the light component of one of saidvortexes 2, it will return after one cycle to its inlet in vortex 2,whereafter it is very likely to merge into the heavy component duringthe following cycle. In the array separator illustrated in the figure,the heavy component is all the time kept in individual vortexes 2 inproximity of the outer periphery, while the light component is collectedinto the central portion of vortexes 2. Due to the distance betweenthem, there is no longer a hazard for different components to mix witheach other. The array separator shown in FIG. 1 is linear but such arraycan also be made arched as well as installed in desired position. Theillustrated vortexes 2 are circular but vortex chambers 1 can also haveother shapes, e.g. elliptical or even polygonal.

Appearing in the section of FIG. 2 is a flat cover of lid 47 for anarray separator as well as a flat bottom 68, both being quite easy tomanufacture, if compared e.g. to cones. The light component outlet pipes13 are in this solution mounted in the middle of each vortex both on lid47 and bottom 68. If desired, it is possible to use just one-sideddischarge for the light fraction. If the light component is dischargedbilaterally through pipes 13, the height of an apparatus can beincreased for increased capacity. If desired, lid 47 and bottom 68 canbe designed to be slightly cup-shaped or ridge-shaped e.g. for increasedrigidity. The outlet or discharge pipes 13 of individual vortexes 2deliver components slightly different from each other in a manner thatthe lightest component is obtained from the first pipe, slightly heaviercomponent from the second etc., until the heaviest of all is obtainedfrom a discharge duct 70 and the second heaviest from the discharge pipe13 associated with the last vortex of an array.

In the section illustrated in FIG. 3, the light component dischargepipes 13 become gradually smaller when proceeding progressively alongvortexes 2 of array 2, 2 . . . Thus, it is possible to receiveapproximately equal component from the discharge pipes 13 of individualvortexes 2. The prior effected assortment and concentration arecompensated for by the reduced amount to be discharged from the rear endvortexes 2. In the case shown in FIG. 3, the height of a supply duct 12is the same as the distance between the ends of pipes 13. If similar orequal components are to be taken from pipes 13, such component can becollected in common containers provided e.g. on top of the lid 47 andunderneath the bottom 68. The quality of components received fromvarious pipes 13 can also be regulated by valves and counter-pressures,the apparatus thus being readily adaptable to varying conditions.

FIG. 4 shows four array separators 2, 2, 2 of the invention, connectedin parallel relationship and providing a single operative unit. Bybacking up vortexes 2 also laterally on other vortexes 2, it has beenpossible to even further reduce the share of a scrubbing wall 1 as wellas that of structural material. The consumption of energy and abrasiondrawbacks are reduced. A large number of vortexes 2 can be fitted in asmall box-like space with no useless intermediate spaces. Flow dividers39 cut a narrow supply or feed flow from ducts 12 further into twoarrays, the feed received by each array 2, 2 . . . being very narrow.Thus, the cross-travelling possibility of the light and heavy componentparticles in desired directions from different edges of the feed isfacilitated. The supply duct 12 can be widened, so that even a smallapparatus produces high capacity. For various applications the width ofa supply duct 12 can be made adjustable.

FIG. 5 shows a solution in which the diameter of vortexes diminisheswhen advancing in a vortex array 2, 2 . . . Thus, a well concentratedheavy component will be obtained from the rear end. If desired, vortexescan also be made so that the diameters thereof grow progressively. Theperformance characteristics of the apparatus can also be adjusted bymodifying the width of area 40. This can be effected e.g. by replacingflow dividers 39.

FIG. 6 illustrates a system provided by two vortex arrays and intendedfor the treatment of long filamentous particles. To avoid adherence tothe impact edge, the apparatus is provided with rounded impact members72.

In the case illustrated in FIG. 7, one vortex 2 serves as a distributormeans from which the flow is distributed into three individual vortexarrays. Individual arrays receive different components according to theorder such arrays meet the flow emerging from a supply duct 12. Theheaviest component will be forced to go into the first branch and thelightest into the last. If desired, the number of branches can beincreased to more than three.

In the case shown in FIG. 8, a flow emerging from a single supply duct12 is branched into 3×3 vortexes. Various components find their mostnatural passages. The heaviest component for example, tends to work itsway nearly linearly 7, towards its own outlet. The discharge pipes ofindividual vortexes may deliver various components. The quality ofvarious components received from various pipes 13 can be regulated bymeans of pipe sizes and counter-pressures. In the solution shown in thefigure, a light fraction discharges from nine defferent vortexes throughpipes 13, the radial flow rate in individual vortexes remaining verylow. Thus, it is possible to separate very small particles indeed, whenthe residence time in vortexes is long. The essential reduction offrictional resistance with respect to traditional helical movementsolutions facilitates the building of very extensive systems, as thewhirl motion can be maintained for a long time. In the solution setforth in FIG. 8, individual vortex arrays are branched and united manytimes.

In a solution displayed in FIG. 9, two vortex arrays 2, 2 . . . arebranched from a single supply point and finally united, so that theheaviest component can be collected from both branches in a singledischarge duct 70.

In a solution shown in FIG. 10, the successive vortexes of a vortexarray 2, 2 . . . are alternately disposed on either side of the averagelongitudinal axis 73. This provides for the heaviest component arelatively linear route through the apparatus, thus alleviating theabrasion problems.

In FIG. 11, there are joined in parallel relationship two vortex arrays2, 2 . . . of FIG. 10, resulting in the reduction of wall surface. Evenmore extensive systems can be made.

In FIG. 12, the last vortex is not at all provided with a lightcomponent discharge pipe 13, whereby the last vortex can be designed asa closed collection container for the heavy component. Said heavycomponent can be discharged e.g. periodically through a shut-off feeder64. Since the last vortex chamber is closed, it receives no actualin-flow but only particles of the heaviest component fly in as a resultof their centrifugal force. The passage of fine component into andwithin coarse component is prevented this way. At the interface betweenthe last vortex and the preceding one there is like an invisible wallfor the light component.

In FIG. 13, the action described in connection with FIG. 12 has beenintensified by passing into the last vortex chamber 1 some scavengingmedium, which flows through a vortex back-up zone 40 slowly into thepreceding vortex 2, rinsing therealong the light particles mixed withthe heavy component. The flow of a scavenging medium 65 runs crosswiserelative to passage 71 of the heavy component.

FIG. 14 shows in principle the deviation between the real center 49 of avortex and the geometric center 67 of a vortex chamber. The flow 63which by-passes vortex 2 urges the vortex center 49 away from itself andthe force of a flow entering said vortex 2 displaces the vortex centerslightly also in the advance direction of a vortex array 2, 2 . . . Inthe preceding figures this deviation has not been illustrated but, inpractical constructions, the discharge pipes 13 should be positioned inthe real vortex center 49. Its position can be determinedexperimentally.

I claim:
 1. A method of sequentially separating a medium into differentcomponents by means of centrifugal force, comprising steps of:forming afirst array of at least three successive separating vortexes alternatelyrotating in opposite flow directions between at least one initial vortexand at least one terminal vortex at spaced-apart at least one entry andat least one discharge ends of the first array, the at least one initialvortexes each being different from the at least one terminal vortexes,with each having a center and defining center lines between adjacentpairs of vortexes, and with each having radially central and radiallyouter vortex portions such that particles having a comparatively largermass concentrate in the outer portion of a vortex and those having acomparatively smaller mass concentrate in the inner portion of a vortex;partially overlapping the at least three successive separating vortexesof the vortex array to substantially back up adjacent separatingvortexes on each other in corresponding interfaces both upstream anddownstream relative to the corresponding center lines and flowdirections and to allow downstream flow of the comparatively larger massparticles between individual adjacent vortexes to run from the outerportion of one vortex into the outer portion of its succeeding vortexwithout any substantial axial movement and in such a way that the flowarea and the backup interfaces of the partially overlapping successiveseparating vortexes is substantially smaller than the flow area of thesuccessive separating vortexes elsewhere; feeding a medium havingdifferent components to be separated including the comparatively largermass particles into said initial ones of the successive separatingvortexes at said at least one entry end of said first array thecomparatively larger mass particles being fed therefrom into one or moreof vortexes intermediate the initial and terminal vortexes of the firstarray of at least three successive separating vortexes, and from there,said particles being further fed into said terminal vortexes forremoval; and separately removing the different components from saidfirst array after separation including removing the comparatively largermass particles from said terminal ones of the successive separatingvortexes of said at least one discharge end thereof.